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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Plasmonic nanostructures for conversion of optical power to electrical power

A plasmoelectric device for conversion of optical power to direct current (DC) electrical power includes a first plasmonic nanostructure having a first resonance value and a second plasmonic nanostructure having a second resonance value. The first and second plasmonic nanostructures are electrically coupled and the first plasmonic nanostructure is configured to receive irradiation at a first irradiation value and the second plasmonic nanostructure is configured to receive irradiation at a second irradiation value, to induce charge transfer between the first and second plasmonic nanostructures.

Sheldon, Matthew↗
DOE OSTI2021

Fluorescence Microscopic Investigations of Molecular Dynamics in Self–Assembled Nanostructures

Many analytical methods employ self-assembled nanostructured materials as chemical recognition media. Molecular permeation through these materials exhibits unique selectivity owing to nanoconfinement-induced enhancement of permeant–nanostructure interactions. This Personal Account introduces our efforts to investigate the detailed dynamics of single or a small number of molecules in nanostructured materials. Here, we developed new experimental and analysis approaches built upon laser-based fluorescence microscopy to measure the detailed translational and orientational dynamics of molecules diffusing in horizontally-oriented, cylindrical nanostructures, including surfactant micelles, silica mesopores, block copolymer microdomains, and bolaamphiphile-based organic nanotubes. Our studies clarified nanoscale details on the structural/chemical heterogeneity of the nanostructures, and their impacts on molecular mass transport dynamics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2010

Tuning the composition and nanostructure of Pt/Ir films via anodized aluminum oxide templated atomic layer deposition.

Nanostructured metal films have been widely studied for their roles in sensing, catalysis, and energy storage. In this work, the synthesis of compositionally controlled and nanostructured Pt/Ir films by atomic layer deposition (ALD) into porous anodized aluminum oxide templates is demonstrated. Templated ALD provides advantages over alternative synthesis techniques, including improved film uniformity and conformality as well as atomic-scale control over morphology and composition. Nanostructured Pt ALD films are demonstrated with morphological control provided by the Pt precursor exposure time and the number of ALD cycles. With these approaches, Pt films with enhanced surface areas, as characterized by roughness factors as large as 310, are reproducibly synthesized. Additionally, nanostructured Ptlr alloy films of controlled composition and morphology are demonstrated by templated ALD, with compositions varying systematically from pure Pt to pure Ir. Lastly, the application of nanostructured Pt films to electrochemical sensing applications is demonstrated by the non-enzymatic sensing of glucose.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Lateral Shifts for Spin Electrons in a Hybrid Magnetic-Electric-Barrier Nanostructure Modulated by Spin-Orbit Couplings

We theoretically investigate how to modulate spin-dependent lateral shifts by the spin-orbit coupling (SOC) in a hybrid magnetic-electric-barrier (MEB) nanostructure, which can be experimentally realized by depositing a ferromagnetic (FM) stripe and a Schottky metal (SM) stripe on the top and bottom of the semiconductor heterostructure, respectively. Two kinds of ROCs, Rashba SOC (RSOC) and Dresselhaus SOC (DSOC), are taken into account fully. The Schrödinger equation of the spin electron in the hybrid MEB nanostructure is exactly solved by using the improved transfer-matrix method (ITMM), and the lateral shift and its spin polarization are numerically calculated with the help of the stationary phase method (SPM). Theoretical analysis indicates that the spin polarization effect in the lateral shift still exists in the hybrid MEB nanostructure when the SOCs are considered. Numerical simulations show that both magnitude and sign of the spin polarization effect in lateral shifts vary strongly with the strengths of RSOC and DSOC. These interesting features may offer an effective means to control the behavior of spin-polarized electrons in the semiconductor nanostructure, and such a hybrid MEB nanostructure serves as a SOC-manipulable spatial spin splitter for spintronic applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2011

TiO{sub 2}/carbon nanotube hybrid nanostructures: Solvothermal synthesis and their visible light photocatalytic activity

MWCNT/TiO{sub 2} hybrid nanostructures were prepared via solvothermal synthesis and sol-gel method with benzyl alcohol as a surfactant. As-prepared hybrid materials were characterized by X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectra and X-ray photoelectron spectroscopy. The results showed that MWCNTs were uniformly decorated with anatase nanocrystals in solvothermal condition, but MWCNTs were embedded in a majority of TiO{sub 2} nanoparticles by sol-gel method. When the weight ratio of MWCNTs to TiO{sub 2} was 20%, MWCNT/TiO{sub 2} hybrid nanostructures prepared by solvothermal synthesis exhibited higher visible-light-driven photocatalytic activity than that prepared by sol-gel method. Post-annealing of MWCNT/TiO{sub 2} nanostructures at 400 deg. C resulted in the formation of the carbonaceous Ti-C bonds on the interface between TiO{sub 2} and MWCNTs, which enhanced the photoabsorbance of the hybrid materials in the visible light region and improved the visible-light degradation efficiency of methylene blue. - Graphical abstract: MWCNT/TiO{sub 2} nanostructures have been prepared by solvothermal method, which exhibited higher visible-light-driven photocatalytic activity than that prepared by sol-gel method. The carbonaceous Ti-C bonds on the interface between TiO{sub 2} and MWCNTs enhanced the photoabsorbance of the hybrid materials in the visible light region. Highlights: > Anatase TiO{sub 2} nanoparticles were anchored on CNTs surface uniformly via solvothermal method {yields} The morphology facilitated the electron transfer between CNTs and TiO{sub 2} {yields} Ti-C bonds extended the absorption of MWCNT/TiO{sub 2} to the whole visible light region. > The hybrid nanostructures showed enhanced visible-light induced photocatalytic activity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Nanostructured dimagnesium manganese oxide (Spinel): Control of size, shape and their magnetic and electro catalytic properties

Tetravalent Mn based ternary oxides are of interest as they are important electrode materials. Dimagnesium manganate (Mg{sub 2}MnO{sub 4}) is one Mn(IV) containing oxide which has been of interest. Nanostructures of the above oxide (spinel) have been obtained by the thermal decomposition of nanostructured metal oxalate precursor at 500 Degree-Sign C. The size and anisotropy of the oxide nanostructures was controlled by choosing appropriate decomposition temperature of the oxalate precursor. Mg{sub 2}MnO{sub 4} nanorods were obtained at low temperature (500 Degree-Sign C), formed by aligned nanoparticles of size{approx}8-10 nm. These nanoparticles show Curie-Weiss behavior with Weiss constant (14 K). Below {approx}50 K there is a small deviation resulting in a negative Weiss constant (-7.36 K) indicating exchange cross over (from ferromagnetic like interactions to antiferromagnetic interactions). The high temperature magnetic moment corresponds to Mn (IV). Electrochemical experiments show that nanostructured Mg{sub 2}MnO{sub 4} is an efficient anode material for oxygen evolution reaction with a current density of 14 mA/cm{sup 2}. The stability of the anode over several cycles of oxidation and reduction is highly encouraging. - Graphical abstract: Nanostructured dimagnesium manganese with efficient electrocatalytic property synthesized by reverse micellar route. Highlights: Black-Right-Pointing-Pointer Mg{sub 2}MnO{sub 4} nanorods were synthesized by reverse micellar route. Black-Right-Pointing-Pointer Anisotropy of oxalate rods retained in oxides nanorods. Black-Right-Pointing-Pointer Nanorods show good catalytic behavior towards oxygen evolution reaction.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Quasi-one-dimensional nanostructured cobalt (Co) intercalated vanadium oxide (V{sub 2}O{sub 5}): Peroxovanadate sol gel synthesis and structural study

Nanostructured cobalt vanadium oxide (V{sub 2}O{sub 5}) xerogels spread onto crystalline Si substrates were synthesized via peroxovanadate sol gel route. The resulting products were characterized by distinct experimental techniques. The surface morphology and the nanostructure of xerogels correlate with Co concentration. The decrease of the structural coherence length is followed by the formation of a loose network of nanopores when the concentration of intercalated species was greater than 4 at% of Co. The efficiency of the synthesis route also drops with the increase of Co concentration. The interaction between the Co(OH{sub 2}){sub 6}{sup 2+} cations and the (H{sub 2}V{sub 10}O{sub 28}){sup 4−} anions during the synthesis was suggested as a possible explanation for the incomplete condensation of the V{sub 2}O{sub 5} gel. Finally the experimental results points for the intercalation of Co between the bilayers of the V{sub 2}O{sub 5}. In this scenario two possible preferential occupation sites for the metallic atoms in the framework of the xerogel were proposed. - Graphical abstract: Quasi-one-dimensional nanostructured cobalt (Co) intercalated vanadium oxide (V{sub 2}O{sub 5}) nanoribbons synthesized by peroxovanadate sol gel route. - Highlights: • Nanostructured cobalt V{sub 2}O{sub 5} gel spread onto c{sub S}i were synthesized via peroxovanadate sol gel route. • The micro and nanostructure correlates with the cobalt content. • The efficiency of the synthesis route shows to be also dependent of Co content. • The experimental results points for the intercalation of Co between the bilayers of the V{sub 2}O{sub 5} xerogel.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Fe{sub 3}O{sub 4} and CdS based bifunctional core–shell nanostructure

Highlights: ► First report on a room temperature aqueous process for growth of a hybrid core shell nanostructure containing a magnetic core and a semiconducting shell. ► Formation of distinct core shell nanostructure revealed by high resolution transmission electron microscopy. ► A bifunctional nature combining magnetic as well as photoresponce for the as synthesised core shell nanostructures demonstrated. ► A tendency towards self organisation of the core–shell nanostructure. ► Possible applications including purification and isolation of biological materials, drug delivery system, bio-labels, spintronics, etc. -- Abstract: A room temperature solution process for synthesis of Fe{sub 3}O{sub 4} nanoparticles and their hybrid core shell nanostructures using CdS as the shell material has been described. The as grown particles have been characterised using XRD, Rietveld refinement, high resolution transmission electron microscopy, atomic force microscopy, superconducting quantum interference device, optical absorbance and photoluminescence spectroscopy. A superparamagnetic response revealed from the magnetisation measurements of the as synthesised magnetite nanoparticles was retained even after the growth of the CdS shell. From luminescence and high resolution atomic force microscopy measurements, it is shown that the core–shell structures advantageously combine magnetic as well as fluorescence response with a tendency towards self-organization.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Co-evaporation of transition metal salt and SiO powder toward copper(or nickel)/silicon-contained composite nanostructures

Graphical abstract: Copper(or nickel)/silicon-contained composite nanostructures were successfully synthesized by co-evaporating SiO powder and corresponding transition metal salts (nickel formate and copper sulfate). Display Omitted Highlights: ► Novel nanostructures were synthesized by co-evaporating SiO and metal salts. ► A pre-sintering process was used in the synthesis of copper/silicon nanocomposites. ► A Ni{sub 31}Si{sub 12}/Si/SiO{sub 2} nanocomposite was obtained. ► Peapod-like copper/silicon-contained nanocomposites were obtained. ► On the basis of experimental results, the formation mechanism was discussed. -- Abstract: We demonstrate that several novel copper(or nickel)/silicon-contained composite nanostructures were successfully synthesized by co-evaporating SiO powder and corresponding transition metal salts (transition metal organic salt and transition metal inorganic salt), including nickel formate, cobalt acetate, and copper sulfate. The morphologies, compositions, and crystal structures of products were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The results indicate that the morphology and composition of formed copper(or nickel)/silicon-contained composite nanostructures are dramatically influenced by the distance between SiO powder and transition metal salts, or by the pre-sintering temperature of the reactants. The possible formation mechanisms of these composite nanostructures were discussed on the basis of experimental observations.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Photoluminescence and photocatalytic properties of BiOCl and Bi{sub 24}O{sub 31}Cl{sub 10} nanostructures synthesized by electrolytic corrosion of metal Bi

Highlights: ► We report a facile method to synthesize bismuth oxychlorides. ► The BiOCl nanosheets have both ultraviolet-blue emission zone and visible emission zone. ► The Bi{sub 24}O{sub 31}Cl{sub 10} nanostructure is a direct electron transition semiconductor. ► The broad and intensive UV emission were observed in Bi{sub 24}O{sub 31}Cl{sub 10} nanostructure. - Abstract: Nanostructured BiOCl and Bi{sub 24}O{sub 31}Cl{sub 10} have been synthesized by electrolytic corrosion of metal Bi. The photocatalysis and photoluminescence (PL) properties of BiOCl and Bi{sub 24}O{sub 31}Cl{sub 10} nanostructures have been investigated. Nanosheets with a thickness of ∼10 nm and in-plane size of 30–60 nm were obtained in the as-synthesized BiOCl. The emission spectra excited at 360 nm consist of two broad emission bands: ultraviolet-blue and visible. The visible emission is responsible for the photocatalytic activity of BiOCl under visible light irradiation. The nanostructured Bi{sub 24}O{sub 31}Cl{sub 10}, self-assembled by uniform nanosheets with a thickness of 10–20 nm, exhibits a broad and strong blue shift UV emission at room temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Structural and optical properties of core–shell Ag{sub 2}S/HgS nanostructures

Graphical abstract: - Highlights: • Core–shell Ag{sub 2}S/HgS nanostructures are successfully synthesized. • The particle size and the structure were confirmed through TEM images. • The absorbance analysis reveals red shift with increasing shell concentration. • A transition from TYPE 1 to TYPE 2 core–shell nanostructure is observed. - Abstract: Here we report on a two-step synthesis route for fabrication of core–shell Ag{sub 2}S/HgS nanostructures. Nanoscale Ag{sub 2}S semiconductors are prepared by a standard redox reaction using AgNO{sub 3} and CS{sub 2} as the reactants in PVP. HgS layers are developed on Ag{sub 2}S cores through S-S bonding at the interface separating the two systems. The properties of these core–shell nanostructures are studied via various spectroscopic and microscopic tools like UV–Vis absorption spectra, photoluminescence spectra, X-ray diffraction pattern and transmission electron microscopic images. Change in optical properties is observed while varying the shell thickness in the sample. A detailed study on the luminescence properties reveal transition from TYPE 1 to TYPE 2 core–shell nanostructures is observed with increasing shell thickness.

36 MATERIALS SCIENCE↗
DOE OSTI2014

One-step synthesis of dense and spherical nanostructured V{sub 2}O{sub 5} particles for cathode of lithium batteries and their electrochemical properties

Graphical abstract: Dense and spherical nanostructured V{sub 2}O{sub 5} particles. - Highlights: • One-step synthesis of dense, spherical, nanostructured V{sub 2}O{sub 5} particles was achieved. • As-prepared V{sub 2}O{sub 5} consists of primary particles of approximately 100 nm size. • The electrochemical performance of spherical nanostructured V{sub 2}O{sub 5} was investigated. • The potential range affects to the discharge capacity and cyclability of V{sub 2}O{sub 5}. - Abstract: A one-step synthesis of V{sub 2}O{sub 5} was directly achieved via ultrasonic spray pyrolysis at various synthesis temperatures ranging from 500 to 700 °C. The V{sub 2}O{sub 5} prepared at 500 °C is dense and spherical nanostructured particles, which consist of primary particles with a size of approximately 100 nm. The morphology change remarkably progresses with increasing synthesis temperatures from 500 to 700 °C. The electrochemical performance of a cathode comprising dense and spherical nanostructured V{sub 2}O{sub 5} particles prepared at 500 °C was investigated by galvanostatic discharge–charge cycling and cyclic voltammetry. From the discharge–charge cycling, the initial discharge capacity of the cathode was found to be about 403 mAh g{sup −1} in the potential range of 1.5–4.0 V, but it decreased owing to inherent phase changes with repeated cycling. The potential range significantly affects the cycle performance, and the V{sub 2}O{sub 5} cathode showed good cycle performance in the potential range of 2.5–4.0 V.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Solvent-controlled preparation and photocatalytic properties of nanostructured TiO{sub 2} thin films with different morphologies

Graphical abstract: Low-temperature growth of nanostructured TiO{sub 2} thin films was presented by a solvent-controlled method. Nanoparticle structured films in anatase phase have been successfully fabricated with some adjustment. The effects of the solvent were investigated and the formation mechanism was proposed. - Highlights: • Nanostructured TiO{sub 2} thin films with different morphologies were obtained at low temperature. • The effects of the solvent on the morphologies of the products were investigated. • The effects of the solvent on the phtocatalytic activity were investigated. - Abstract: A low-temperature growth method of nanostructured TiO{sub 2} thin films with different morphologies was reported. Rod-like, grass-like and nanosheet structured films have been successfully fabricated just by adjusting the ratio of different solvents. The effects of the solvent on the morphologies of the TiO{sub 2} nanostructures were investigated. The formation mechanism of different morphologies was proposed based on the experiment results. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The photocatalytic activity of as-prepared samples for the degradation of methylene blue (MB) in water was evaluated under UV illumination. Results showed that the solvents exhibited important effect on the morphologies and photocatalytic activity of as-prepared nanostructured titania films.

36 MATERIALS SCIENCE↗
DOE OSTI2014

A biotemplated nickel nanostructure: Synthesis, characterization and antibacterial activity

Highlights: • Nickel nanostructure-encapsulated bacteria were prepared using electroless deposition. • Bacterium surface was activated by red-ox reaction of its surface amino acids. • Interfacial changes at cell surfaces were investigated using fluorescence spectroscopy. • TEM and AFM depicted morphological changes. • Antibacterial activity of nanostructure was examined against different bacteria strains. - Abstract: Nickel nanostructure-encapsulated bacteria were prepared using the electroless deposition procedure and activation of bacterium cell surface by red-ox reaction of surface amino acids. The electroless deposition step occurred in the presence of Ni(II) and dimethyl amine boran (DMAB). Interfacial changes at bacteria cell surfaces during the coating process were investigated using fluorescence spectroscopy. Fluorescence of tryptophan residues was completely quenched after the deposition of nickel onto bacteria surfaces. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) depicted morphological changes on the surface of the bacterium. It was found that the Ni coated nanostructure was mechanically stable after ultrasonication for 20 min. Significant increase in surface roughness of bacteria was also observed after deposition of Ni clusters. The amount of coated Ni on the bacteria surface was calculated as 36% w/w. The antibacterial activity of fabricated nanostructure in culture media was examined against three different bacteria strains; Escherichia coli, Bacillus subtilis and Xantomonas campestris. The minimum inhibitory concentrations (MIC) were determined as 500 mg/L, 350 mg/L and 200 mg/L against bacteria, respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Three-dimensional flowerlike iron oxide nanostructures: Morphology, composition and metal ion removal capability

Graphical abstract: The iron alkoxide precursors are calcined into α-Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4} microstructures with different morphologies by changing calcination atmosphere, reaction time of precursors and calcination temperature simply. The Fe{sub 2}O{sub 3}/Ag hybrid composites prepared through aqueous synthesis and light irradiation. - Highlights: • α-Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} microstructures with different morphologies were created. • Solvents play an important role for the solvothermal treatment of precursors. • The α-Fe{sub 2}O{sub 3} microstructures show excellent adsorption properties. • Fe{sub 2}O{sub 3}/Ag hybrid composites were prepared to improve their properties. - Abstract: The flower-like precursors of Fe alkoxide constructed by the self-assembly of nanoflakes were prepared. Time-dependent experiments confirmed the formation mechanism of flower-like precursors. After calcination, α-Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} nanostructures with different morphologies were created. Fe{sub 3}O{sub 4} nanostructures containing blocks with a truncated octahedron structure were obtained under N{sub 2} protection. α-Fe{sub 2}O{sub 3} nanostructures were prepared in an air atmosphere. The values of maximum adsorption capacity of α-Fe{sub 2}O{sub 3} nanostructures for Cr{sup 6+} ions were much higher than that of commercial bulk α-Fe{sub 2}O{sub 3}. Ag NPs were deposited on α-Fe{sub 2}O{sub 3} nanostructures through an aqueous synthesis and light irradiation using L-cysteine as a linker. Such procedure is utilizable for the preparation of the composites of noble metals and magnetic materials.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Characteristics of Co3O4 and cobalt nanostructured microspheres: Morphology, structure, reduction process, and magnetic properties

Highlights: • The metal cobalt samples consist in both α-Co with a hexagonal close-packed lattice and β-Co face-centered cubic crystal at reduction temperatures 220, 240, 300 and 350 °C. • Co{sub 3}O{sub 4} reduction proceeded in successive stages: water removal, residual salt removal, Co{sub 3}O{sub 4} → CoO and CoO → Co transitions. • Inheritance of morphology may have droplet–Co{sub 3}O{sub 4}–Co association. - Abstract: Nanostructured magnetic cobalt microspheres were synthesized using a two-stage method. First, nanostructured cobalt oxide Co{sub 3}O{sub 4} microspheres were produced by ultrasonic spray pyrolysis at different temperatures from 800 to 1100C. Second, the nanostructured powders obtained were reduced to metal cobalt in an hydrogen atmosphere at different temperatures from 220 to 350C. In this study the evolution of the morphology from Co{sub 3}O{sub 4} nanostructured microspheres to nanostructured Co, resulting from the Co{sub 3}O{sub 4} reduction process, and the structure of metal cobalt, were investigated. It was found that the metal cobalt agglomerates have the same shape and mean diameter (∼ 1,5 μm) as those of the cobalt oxide, Co{sub 3}O{sub 4}. The amount of Co microspheres with smaller diameters decreased with increasing reduction temperature. Also, the β-Co content increased with increasing reduction temperature.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Self-Sorting vs Coassembly in Peptide Amphiphile Supramolecular Nanostructures

The functionality of supramolecular nanostructures can be expanded if systems containing multiple components are designed to either self-sort or mix into coassemblies. This is critical to gain the ability to craft self-assembling materials that integrate functions, and our understanding of this process is in its early stages. Here, in this work, we have utilized three different peptide amphiphiles with the capacity to form β-sheets within supramolecular nanostructures and found binary systems that self-sort and others that form coassemblies. This was measured using atomic force microscopy to reveal the nanoscale morphology of assemblies and confocal laser scanning microscopy to determine the distribution of fluorescently labeled monomers. We discovered that PA assemblies with opposite supramolecular chirality self-sorted into chemically distinct nanostructures. In contrast, the PA molecules that formed a mixture of right-handed, left-handed, and flat nanostructures on their own were able to coassemble with the other PA molecules. We attribute this phenomenon to the energy barrier associated with changing the handedness of a β-sheet twist in a coassembly of two different PA molecules. This observation could be useful for designing biomolecular nanostructures with dual bioactivity or interpenetrating networks of PA supramolecular assemblies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Ultrafast carrier dynamics in bimetallic nanostructure-enhanced methylammonium lead bromide perovskites

In this paper, we examine the impact of hybrid bimetallic Au/Ag core/shell nanostructures on the carrier dynamics of methylammonium lead tribromide (MAPbBr 3 ) mesoporous perovskite solar cells (PSCs). Plasmon-enhanced PSCs incorporated with Au/Ag nanostructures demonstrated improved light harvesting and increased power conversion efficiency by 26% relative to reference devices. Two complementary spectral techniques, transient absorption spectroscopy (TAS) and time-resolved photoluminescence (trPL), were employed to gain a mechanistic understanding of plasmonic enhancement processes. TAS revealed a decrease in the photobleach formation time, which suggests that the nanostructures improve hot carrier thermalization to an equilibrium distribution, relieving hot phonon bottleneck in MAPbBr3 perovskites. TAS also showed a decrease in carrier decay lifetimes, indicating that nanostructures enhance photoinduced carrier generation and promote efficient electron injection into TiO 2 prior to bulk recombination. Furthermore, nanostructure-incorporated perovskite films demonstrated quenching in steady-state PL and decreases in trPL carrier lifetimes, providing further evidence of improved carrier injection in plasmon-enhanced mesoporous PSCs.

36 MATERIALS SCIENCE↗